The Role of miRNAs in Dexmedetomidine's Neuroprotective Effects against Brain Disorders

Exosomes derived from umbilical cord-mesenchymal stem cells inhibit the NF-κB/MAPK signaling pathway and reduce the inflammatory response to promote recovery from spinal cord injury

Spinal cord injury (SCI) is a serious traumatic disease of the central nervous system and leads to incomplete or complete loss of the body's autonomous motor and sensory functions, seriously endangering human health. Recently, exosomes have been proposed as important substances in cell-to-cell interactions. Mesenchymal stem cell (MSC)-derived exosomes exert good therapeutic effects and play a crucial role in neurological damage repair. However, the detailed mechanisms underlying their effects remain unknown. Herein, we found that compared to SCI rats, those subjected to umbilical cord MSC (UC-MSC)-derived exosomes injection showed an improved motor ability. Nevertheless, the transcriptome of BV2 microglia in different treatment groups indicated that the action pathway of exosomes might be the NF-κB/MAPK pathway. Additionally, exosomes from UC-MSCs could inhibit P38, JNK, ERK, and P65 phosphorylation in BV2 microglia and SCI rat tissues. Moreover, exosomes could inhibit apoptosis and inflammatory reaction and reactive oxygen species (ROS) production of BV2 microglia in vitro and in vivo. In conclusion, UC-MSCs-derived exosomes might protect SCI in rats by inhibiting inflammatory response via the NF-κB/MAPK signaling pathway, representing novel treatment targets or approaches for SCI.

Bioinformatics analysis of differentially expressed genes related to ischemia and hypoxia in spinal cord injury and construction of miRNA-mRNA or mRNA-transcription factor interaction network

BACKGROUND

Previous studies show that spinal cord ischemia and hypoxia is an important cause of spinal cord necrosis and neurological loss. Therefore, the study aimed to identify genes related to ischemia and hypoxia after spinal cord injury (SCI) and analyze their functions, regulatory mechanism, and potential in regulating immune infiltration.

METHODS

The expression profiles of GSE5296, GSE47681, and GSE217797 were downloaded from the Gene Expression Omnibus database. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to determine the function and pathway enrichment of ischemia- and hypoxia-related differentially expressed genes (IAHRDEGs) in SCI. LASSO model was constructed, and support vector machine analysis was used to identify key genes. The diagnostic values of key genes were evaluated using decision curve analysis and receiver operating characteristic curve analysis. The interaction networks of miRNAs-IAHRDEGs and IAHRDEGs-transcription factors were predicted and constructed with the ENCORI database and Cytoscape software. CIBERSORT algorithm was utilized to analyze the correlation between key gene expression and immune cell infiltration.

RESULTS

There were 27 IAHRDEGs identified to be significantly expressed in SCI at first. These genes were mostly significantly enriched in wound healing function and the pathway associated with lipid and atherosclerosis. Next, five key IAHRDEGs (Abca1, Casp1, Lpl, Procr, Tnfrsf1a) were identified and predicted to have diagnostic value. Moreover, the five key genes are closely related to immune cell infiltration.

CONCLUSION

Abca1, Casp1, Lpl, Procr, and Tnfrsf1a may promote the pathogenesis of ischemic or hypoxic SCI by regulating vascular damage, inflammation, and immune infiltration.

Dexmedetomidine mitigates neuroinflammation in an Alzheimer's disease mouse model via the miR-204-3p/FBXL7 signaling axis

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder characterized by neuroinflammation. Dexmedetomidine (Dex) is known for its neuroprotective properties in clinical settings. In this study, we investigated the potential of Dex in protecting against neuroinflammation in an AD mouse model induced by amyloid-beta (Aβ) injection. First, in the AD mouse model, Aβ injection were administered, and the model was confirmed through behavioral tests, including the Morris water maze and Y-maze. Neuroinflammatory states in Aβ-injected mice were assessed using hematoxylin and eosin staining and enzyme-linked immunosorbent assay. Expression levels of microRNA (miR)-204-3p and F-box/LRR-repeat protein 7 (FBXL7) in mouse tissues were determined through real-time quantitative polymerase chain reaction and Western blot. The binding interaction between miR-204-3p and FBXL7 was elucidated using dual-luciferase analysis. Aβ-injected mice exhibited cognitive impairment, neuroinflammation, and downregulated miR-204-3p. Upregulation of miR-204-3p reduced inflammatory infiltration and mitigated neuroinflammation in Aβ-injected mice. Dex treatment reduced inflammation in hippocampal tissues of Aβ-injected mice. Dex treatment upregulated miR-204-3p, leading to suppressed FBXL7 expression in tissues. Inhibition of miR-204-3p or overexpression of FBXL7 reversed the alleviating effect of Dex on neuroinflammation in Aβ-injected mice. Overall, Dex increased miR-204-3p expression, resulting in the inhibition of FBXL7, and subsequently alleviated neuroinflammation in Aβ-injected mice.

The effects of dexmedetomidine on trauma-induced secondary injury in rat brain

BACKGROUND

The objective of this study was to investigate the effect of dexmedetomidine (Dex), a sedative drug with little or no depressant effect on respiratory centers, on secondary injury in rat brain tissue by means of the Na+/K+ ATPase enzyme, which maintains the cell membrane ion gradient; malondialdehyde, an indicator of membrane lipid peroxidation; glutathione, an indicator of antioxidant capacity; and histopathological analyses.

METHODS

Eighteen rats were randomized into three groups: the trauma group received anesthesia, followed by head trauma with a Mild Traumatic Brain Injury Apparatus; the Trauma+Dex group received an additional treatment of 100 µg/kg intraperitoneal dexmedetomidine daily for three days; the Control group received anesthesia only.

RESULTS

The highest MDA levels compared to the Control group were found in the Trauma group. Mean levels in the Trauma+Dex group were lower, albeit still significantly high compared to the Control group. Glutathione levels were similar in all groups. Na/K-ATPase levels were significantly lower in the Trauma group compared to both the Control group and the Trauma+Dex group. Histopathologic findings of tissue degeneration including edema, vascular congestion and neuronal injury, and cleaved caspase-3 levels were lower in the Trauma+Dex group compared with the Trauma group.

CONCLUSIONS

Dexmedetomidine administered during the early stage of traumatic brain injury may inhibit caspase-3 cleavageHowever, the mechanism does not seem to be related to the improvement of MDA or GSH levels.

MicroRNA-323-5p Involved in Dexmedetomidine Preconditioning Impart Neuroprotection

Background and Objectives: Cerebral ischemia is one of the major preoperative complications. Dexmedetomidine is a well-known sedative-hypnotic agent that has potential organ-protective effects. We examine the miRNAs associated with preconditioning effects of dexmedetomidine in cerebral ischemia. Materials and Methods: Transient infarcts were induced in mice via reperfusion after temporary occlusion of one side of the middle cerebral artery. A subset of these mice was exposed to dexmedetomidine prior to cerebral infarction and miRNA profiling of the whole brain was performed. We administered dexmedetomidine and miRNA-323-5p mimic/inhibitor to oxygen-glucose deprivation/reoxygenation astrocytes. Additionally, we administered miR-323-5p mimic and inhibitor to mice via intracerebroventricular injection 2 h prior to induction of middle cerebral artery occlusion. Results: The infarct volume was significantly lower in the dexmedetomidine-preconditioned mice. Analysis of brain samples revealed an increased expression of five miRNAs and decreased expression of three miRNAs in the dexmedetomidine-pretreated group. The viability of cells significantly increased and expression of miR-323-5p was attenuated in the dexmedetomidine-treated oxygen-glucose deprivation/reoxygenation groups. Transfection with anti-miR-323-5p contributed to increased astrocyte viability. When miRNA-323-5p was injected intraventricularly, infarct volume was significantly reduced when preconditioned with the miR-323-5p inhibitor compared with mimic and negative control. Conclusions: Dexmedetomidine has a protective effect against transient neuronal ischemia-reperfusion injury and eight specific miRNAs were profiled. Also, miRNA-323-5p downregulation has a cell protective effect under ischemic conditions both in vivo and in vitro. Our findings suggest the potential of the miR-323-5p inhibitor as a therapeutic agent against cerebral infarction.

Role and regulatory mechanism of microRNA mediated neuroinflammation in neuronal system diseases

MicroRNAs (miRNAs) are small non-coding RNAs with the unique ability to degrade or block specific RNAs and regulate many cellular processes. Neuroinflammation plays the pivotal role in the occurrence and development of multiple central nervous system (CNS) diseases. The ability of miRNAs to enhance or restrict neuroinflammatory signaling pathways in CNS diseases is an emerging and important research area, including neurodegenerative diseases, stroke, and traumatic brain injury (TBI). In this review, we summarize the roles and regulatory mechanisms of recently identified miRNAs involved in neuroinflammation-mediated CNS diseases, aiming to explore and provide a better understanding and direction for the treatment of CNS diseases.

Opioids Alleviate Oxidative Stress via the Nrf2/HO-1 Pathway in LPS-Stimulated Microglia

Opioids are known to have antioxidant effects and to modulate microglial function under certain conditions. It has been previously shown that opioid ligands can effectively inhibit the release of proinflammatory cytokines when stimulated with lipopolysaccharide (LPS) and convert microglia to an anti-inflammatory polarization state. Here, we used C8-B4 cells, the mouse microglial cell line activated by LPS as a model to investigate the anti-inflammatory/antioxidant potential of selected opioid receptor agonists (DAMGO, DADLE, and U-50488). We found that all of these ligands could exert cytoprotective effects through the mechanism affecting LPS-induced ROS production, NADPH synthesis, and glucose uptake. Interestingly, opioids elevated the level of reduced glutathione, increased ATP content, and enhanced mitochondrial respiration in microglial cells exposed to LPS. These beneficial effects were associated with the upregulation of the Nrf2/HO-1 pathway. The present results indicate that activation of opioid signaling supports the preservation of mitochondrial function with concomitant elimination of ROS in microglia and suggest that an Nrf2/HO-1 signaling pathway-dependent mechanism is involved in the antioxidant efficacy of opioids. Opioid receptor agonists may therefore be considered as agents to suppress oxidative stress and inflammatory responses of microglia.

The Effects of Dexmedetomidine on Abdominal Aortic Occlusion-Induced Ovarian Injury via Oxidative Stress and Apoptosis

Ischemia/reperfusion (I/R) induced ovarian damage is caused by various diseases such as ovarian torsion, ovarian transplantation, cardiovascular surgery, sepsis, or intra-abdominal surgery. I/R-related oxidative damage can impair ovarian functions, from oocyte maturation to fertilization. This study investigated the effects of dexmedetomidine (DEX), which has been shown to exhibit antiapoptotic, anti-inflammatory, and antioxidant effects, on ovarian I/R injury. We designed four study groups: group 1 (n = 6): control group; group 2 (n = 6): only DEX group; group 3 (n = 6): I/R group; group 4 (n = 6): I/R + DEX group. Then, ovarian samples were taken and examined histologically and immunohistochemically, and tissue malondialdehyde (MDA) and glutathione (GSH) levels were measured. In the I/R group MDA levels, caspase-3, NF-κB/p65, 8-OHdG positivity, and follicular degeneration, edema, and inflammation were increased compared to the control group (p = 0.000). In addition, GSH levels were significantly decreased in the I/R group compared to the control group (p = 0.000). On the other hand, in the I/R + DEX treatment group MDA levels, caspase-3, NF-κB/p65, 8-OHdG positivity, follicular degeneration, edema, and inflammation findings were decreased than in the I/R group (p = 0.000, p = 0.005, p = 0.005, p = 0.001, p = 0.005, respectively). However, GSH levels increased significantly in the I/R + DEX treatment group compared to the I/R group (p = 0.000). DEX protects against ovarian I/R injury through antioxidation and by suppressing inflammation and apoptosis.

Dexmedetomidine protects against Ropivacaine-induced neuronal pyroptosis via the Nrf2/HO-1 pathway

Dexmedetomidine (DEX) has been demonstrated to protect against ropivacaine (Ropi)-induced neuronal damages. This study was conducted to explore the protective role of DEX in Ropi-induced neuronal pyroptosis and provide a strategy to eliminate Ropi-induced neurotoxicity. The impacts of different concentrations of Ropi and DEX on neurotoxicity in SK-N-SH cells were evaluated by cell counting kit-8 assay and lactic dehydrogenase assay kits. Levels of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1), NLR family pyrin domain containing 3 (NLRP3), cleaved Caspase-1, cleaved N-terminal gasdermin D, interleukin (IL)-1β, and IL-18 were measured by real-time quantitative PCR, Western blotting, and enzyme linked immunosorbent assay. The Nrf2 level after nuclear/cytoplasmic separation was quantified. SK-N-SH cells were treated with si-Nrf2, Nigericin (NLRP3 activator), and Zinc Protoporphyrin (HO-1 inhibitor) to validate the mechanism. Ropi reduced SK-N-SH cell viability in a concentration- and time-dependent manner. DEX treatment alleviated Ropi-induced toxicity and inhibited pyroptosis. Ropi increased the expression levels of Nrf2 and HO-1, and DEX further enhanced the increases and promoted Nrf2 nuclear translocation. Nrf2/HO-1 inhibition or NLRP3 activation both neutralized the inhibitory role of DEX in Ropi-induced pyroptosis of SK-N-SH cells. Overall, DEX promoted the Nrf2/HO-1 pathway to inhibit NLRP3 expression, thus alleviating Ropi-induced neuronal pyroptosis.

Integrated Analysis of Transcriptome and microRNA Profile Reveals the Toxicity of Euphorbia Factors toward Human Colon Adenocarcinoma Cell Line Caco-2

Euphorbia factors, lathyrane-type diterpenoids isolated from the medical herb Euphorbia lathyris L. (Euphorbiaceae), have been associated with intestinal irritation toxicity, but the mechanisms underlying this phenomenon are still unknown. The objective of this study was to evaluate the transcriptome and miRNA profiles of human colon adenocarcinoma Caco-2 cells in response to Euphorbia factors L1 (EFL1) and EFL2. Whole transcriptomes of mRNA and microRNA (miRNA) were obtained using second generation high-throughput sequencing technology in response to 200 μM EFL treatment for 72 h, and the differentially expressed genes and metabolism pathway were enriched. Gene structure changes were analyzed by comparing them with reference genome sequences. After 72 h of treatment, 16 miRNAs and 154 mRNAs were differently expressed between the EFL1 group and the control group, and 47 miRNAs and 1101 mRNAs were differentially expressed between the EFL2 group and the control. Using clusters of orthologous protein enrichment, the sequenced mRNAs were shown to be mainly involved in transcription, post-translational modification, protein turnover, chaperones, signal transduction mechanisms, intracellular trafficking, secretion, vesicular transport, and the cytoskeleton. The differentially expressed mRNA functions and pathways were enriched in transmembrane transport, T cell extravasation, the IL-17 signaling pathway, apoptosis, and the cell cycle. The differentially expressed miRNA EFLs caused changes in the structure of the gene, including alternative splicing, insertion and deletion, and single nucleotide polymorphisms. This study reveals the underlying mechanism responsible for the toxicity of EFLs in intestinal cells based on transcriptome and miRNA profiles of gene expression and structure.